The invention relates to an automotive side-impact protection system comprising an inflatable elongated cushioning bag having a pair of tensioning straps for tensioning the bag in an inflated condition between the two fixed points in a vehicle.
In such a protection system the inflated cushioning bag extends from the roof edge of the vehicle downwards to the door shoulder line as well as between the A pillar and C pillar of the vehicle so that both the side windows as well as the B pillar are surface covered. The general intention is to tension the inflated cushioning bag between a point at the bottom end of the A pillar and a point on the C pillar so as to cushion transverse forces produced by the side-impact, on the one hand, and, on the other hand, to promote deployment of the cushioning bag. Since in its resting condition the cushioning bag is stowed away in the vehicle with the front and rear tensioning strap along a curved roof edge whilst the lower edge portion of the cushioning bag in the inflated condition is substantially straight, however, tensioning the inflated cushioning bag in the vehicle is attainable only by special means. It has already been proposed to divide the gas bag into several chambers extending parallel and perpendicular so that the curvatures of the individual chambers result in a natural shortening of the cushioning bag longitudinally. Experience has shown, however, that this shortening is not sufficient to effectively tension the cushioning bag in the vehicle. It has also been proposed to apply an active tensioning by, e.g. pyrotechnically activated tensioning means like those of a belt retractor. The engineering of this solution is, however, highly complicated.
The invention provides an automotive side-impact protection system which assures the desired tensioning of the inflated cushioning bag in the vehicle by very simple means in making use of existing geometry. According to the invention at least one of the tensioning straps is branched at its end facing the cushioning bag into two tensioning strap sections engaging the inflated cushioning bag at different levels. In the resting condition of the cushioning bag these two tensioning strap sections lie on top of each other according to the contour of the roof edge, along which the tensioning straps are stowed with the folded cushioning bag. On deployment and expansion of the cushioning bag the two tensioning strap sections are splayed, however, since they are joined to each other at the end of the tensioning strap and connected to the inflated cushioning bag at different levels. This splaying of the two tensioning strap sections produces a shortening of the effective tensioning line by roughly half the length of a tensioning strap section. It is this shortening of the effective tensioning line that is made use of to tension the inflated cushioning bag between two fixed points in the vehicle.
This shortening of the effective tensioning line achieved in this way is all the more effective, the greater the angle formed by the two tensioning strap sections to each other in the inflated condition of the cushioning bag. In the preferred embodiment the tensioning strap sections thus form between them an obtuse angle in the tensioned condition. However, a useful shortening is also possible with smaller angles, although the angle should not be less than 45xc2x0.
The shortening of the effective tensioning line achieved by the invention is also all the more, the longer the two tensioning strap sections are. This is why in the preferred embodiment the end of one of the tensioning strap sections is connected to the lower edge portion of the inflated cushioning bag and the end of the other tensioning strap section engages the inflated cushioning bag roughly in the middle or even higher.